A cellular communications network can include a radio network made up of a number of radio cells or “cells”. Each cell can be served by at least one fixed-location transceiver or “cell tower” in this specification. The cells can cover different land areas to provide radio coverage over a wider area than can be covered by a single transceiver. A variable number of mobile devices (e.g., cellular phones) can be used in any one cell. The mobile devices can make and receive telephone calls or transmit and receive data because the mobile devices can be connected over the air to a nearby cell tower. A mobile device can move from one cell to another during transmission, thereby switching cell towers to which the mobile device is connected. The mobile device “knows” the cell tower that is currently connected to the mobile device by an identifier of the cell tower (e.g., a cell identifier). A location of a cell, if known, can be used to determine an approximate geographic location of the mobile device. However, a cell can cover a large geographic area (e.g., a circle having radius of a kilometer or more). Therefore, the estimate can lack accuracy. Furthermore, the exact location of a cell tower does not necessarily coincide with the location of the mobile devices.